Joint structure for metal tubing



June 6 .1944. Q BOOTH 2,350,582

JOINT STRUCTURE FOR METAL TUBING Filed Sept. 27, 1943 INVENTOR. [/9191 (1.500771 BY Patented June 6, 1944 JOINT STRUCTURE FOR METAL .TUBING,

- EarlC. Booth, Columbus, ma.,assignor to Name;

Sparks Inclustries,"Inc.,Columbus, Ind.,.a. corporation of Indiana- Application September 27, is aserial No. 503,935 7 Claims. (01. 287-119) .It the object of my invention to interconnect two alined metal tubes of the same or nearly the,

same diameterina manner which will be effective and which, at the same time, will provide a pleasing appearance.

In carrying out my invention, I provide near one end of one of theztubes a circumferential series of coplanar, arcuate slots, and I deflect the material between each slot and the adjacent end of the tube radially inwardly to form a. flutej.

The lands left between flutes are then collapsed radially of the tube to the extent necessary to permit their insertion telescopically into the other tube. In that other tube, I provide diametrically opposite bolt holes and deflect the metal around each such bolt hole inwardly to form a frusto-conical flange of such a size and shape that it will bear against the sides of a flute on the first-named tube when the two tubes are telescopically associated. At the bottom of two diametrically opposite flutes of the first named tube, I provide a pair of bolt holes so positioned as to be alined with the bolt holes in the other tube when the two tubes are in telescopically associated position. A bolt through the alined bolt holes holds the two tubes in interconnected relationship.

The accompanying drawing illustrates my invention: Fig. 1 is a side elevation of a joint between two alined tubes; Fig. 2 is a transverse section on the line 22 of Fig. 3; Fig. 3 is an axial section on the line 3-3 of Fig. 2; Figs.

4 and 5 are end and side elevations of the fluted tube showing its shape after the initial forming operation; and Figs. 6 and '7 are end and side elevations of the fluted tube at the completion of the forming operations.

The drawing illustrates two tubes III and II which are of equal diameter and which are to be interconnected. One of these tubes, here shown as the tube II, is formed at its end to provide a series of flutes I2 separated by lands I3. In the preferred method of forming the flutes I2 and lands I3, the tube-wall is sheared through at the inner end of each flute to leave between adjacent lands l3 an axially presented surface I4. Figs. 4 and 5 illustrate the end of the tube II at the completion of the initial forming operation.

After the tube-end has been formed as indicated in Figs. 4 and 5, it is subjected to a second forming operation in which the lands I3 are offset inwardly to an extent such that the fluted end of the tube I I may be received within the end of the tube III. The end of the tube II as thus formed is indicated in Figs. 6 and. 7. To complete the end of the tube II, alined holes-I5 are provided in the basesof two diametrically opposite flutes I2. .Z v

At. a distance'from the end of the tube I0 equal to. the distance between the holes I5 and surfaces I4 on the tube II, thetube III is' providedv with two diametricallyopposite. holes IT. The material at the end of each of'the holes I1 is deflected inwardly to form a frusto-conical flange; I8, such flange desirably being shaped so that it will beargaga'inst. the sides of one of the flutes I2 of vthetube II, inthe manner'illustrated inFig.- 2.. I 3 Y '1.

To complete the joint, a bolt 20 is passed through the alined holes I5 and I8. If desired, the bolt 20 may be of the countersunk-head type so that the head will be received within one of the frusto-conical flanges I 8 and a frustoconical washer 2| fitting the other flange I8, may be employed beneath the nut 22 of the bolt 20.

The joint illustrated in the drawing is particularly suitable for use in metal furniture-of a type whose assembly requires the joining of alined tubes of the same diameter. Because of the fit of the flanges I8 within the flutes I2, the joint is effective in transmitting torsional stresses from one tube to the other. With the end of the tube III engaging the axially presented surfaces I4 on the tube II, the joint is adapted to transmit axial thrusts from one tube to the other, and, in addition, possesses a smooth appearance.

I claim as my invention:

1. In combination, a metal tube provided near one end with a circumferential series of coplanar, arcuate slots, the tube metal between each slot and the adjacent tube-end being displaced radially inwardly to form a flute, the lands left between said flutes being displaced radially inwardly to an extent suflicient to permit the entry of the fluted tube-end into a tube of the same diameter, a second tube of the same diameter as the first, the fluted end of the first tube being telescopically received Within the second and the end surface of the latter abutting against the sides of the slots in the former, and means for preventing axial separation of said tubes.

2. The invention set forth in claim 1 with the addition that said second tube is provided interiorly with means engaging one or more sides of the flutes on the first tube to prevent relative rotation of the two tubes.

3. In combination, a metal tube provided near one end with a circumferential series of coplanar,

arcuate slots, the tube metal between each slot and the adjacent tube-end being displaced radially inwardly to form a flute, the lands left between said flutes being displaced radially inwardly to an extent sufficient to permit the entry of the fluted tube-end into a tube of the same diameter, a second tube of the same diameter as the first,t..theo fluted ,.end. of the .first tubelbeing telescopically receivediwithin the second and the V of the latter abutting against the sides of the end surface of the latter abutting against the sides of the slots in the former, the telescopically associated ends of said two tubes being providedf withalined holes for the receptiomof atrans-r versely extending bolt, a bolt passing throughsaidt displaced inwardly to engage the sides of flutes on the first tube.

' 5. In combination, a metal tube provided near one end with a circumferential series of coplanar, arcuate slots, the tube metal between each slot and the adjacent tube-end being displaced radially inwardly to form a flute, a second tube, the fluted. end of the first .tube.lbeing .,telescopically receivedwi-thin the secondand the endtsurface slots in the former, and means for preventing axial separation of said tubes.

6.'In combination,=-a metal tube provided near one. .endwithacircumferential series of coplanar,

holes, the tube-metal around;atl ast'onesotsaid; :,arcuatehslots; thehtube metal between each slot holes in the second tube being displaced inwardly to engage the sides of flutes on the first tube.

4. In combination, a metal tube -provided near one end withv a circumferential series of coplanan. arcuate slots, the tube metal between each slot" and. the a adj acent itube+end -beingadi'splace d. radlally inwardly totformta zflute; the "lands. left'cbe tween said flutes being displaced radiallyrinwardly to an extent. sufficient :to' p'ermittthe entr-y of .the fluted. tube-endziinto :aitubeoof the same diameter; a .secondsktube iofiithe same diameter as. the.:first,-i the: fluted iend iofdzhefirst tube being I telescopically:received withm 'the second-, -the telescopicaliy 'associated Lends of-fsai'd itwo'tubes be- 1 and th egadiacent tube-end being displaced radially inwardly to form a flute, a second tube, the fluted-end 0f the first tube being telescopically receivedwithin the second, the telescopically associated ends of said two tubes being provided with alined holes forthe reception of a transversely extending bolt, a bolt' passin'g throughsaidnzhol'sy the -tube-metal--'aroun'd at least one of said holes invtheseconditub'e being displaced inwardly to engage the sides of "flutes'on the- 7. The-: invention set'forth-inblaim 5 with the addition that said second tubeds provided interiorlywith means A engaging *one or more sides ing providedwithalinedoholessforithei reception of the flutes *on thefirsttubeto prevent relative of a transversely;extendinglboltgaubolt passing through: saidz'zhols, the tubeametal i'around'= at least one of said holes in the secondiftube beingrotation of the two tubes I V EARL CL BOOTH: 

